Assuming this is MS band and not a 2nd year of beginning band. I structure it around the concerts/contest, and it depends on the class.

Fall = 3-5 Stand Tunes for pep rallies (Louie Louie, Hey Song are always a part of this)
October = Start on the Christmas Music (3 pieces)
Spring = UIL concert pieces
Spring After UIL = 1 to 2 extra/fun pieces for the Spring Concert. This depends on the group and how close the Spring Concert is to UIL. If they struggle, they may not change anything between UIL and the Spring Concert even if there is time...but that's if they're really struggling.

So, 9 to 12 full band pieces a year depending on the group. 5-8 of those being concert pieces (in case one of the Christmas pieces is also a UIL piece).